Perhaps others have had different experiences, but I have driven back and forth between Switzerland and Germany in numerous locations from Basel as far east as Konstanz, and have never been controlled. If you zoom in on this border you will be amazed at how intricate it is. Just east of Schaffhausen you will even see an enclave of Germany completely surrounded by Switzerland. I am sorry that I cannot say if things at the Austrian border are more formal. One wonders how all this might change with the recent election in Austria.

I was in Konstanz, Germany last year. The Swiss flock over the border to take advantage of the lower German prices. There was no sign of any border control on the road into Konstanz.

We travelled by train daily between Germany and Switzerland for a week and never saw anyone who looked as though they were interested in policing a border. Same at Basel when arriving from Frankfurt on the train.

The Swiss cross over the border into Germany in droves to shop at food stores such as Edeka and Kaufland in numerous places, including the aforementioned Konstanz and also at Waldshut, Laufenburg, Bad Säckingen, Rheinfelden, and even Lörrach. I have checked the parking lots in Waldshut and Laufenburg and have noticed that well over half of the vehicles have Swiss licence plates. Sometimes they load their vehicles with so much that I wonder where they fit in their kids. Similarly, over in France, most of the cars at Carrefour and Intermarché in Morteau are Swiss-registered, probably most from nearby La Chaux-de-Fonds. Pontarlier is a favoured grocery shopping city for some Neuchâtelois and also Vaudois. Not only are food prices lower in Germany and France, but Swiss shoppers can apply to be de-taxed (VAT) which further reduces the prices. By the way, the entry points to Switzerland from France are manned by Swiss douaniers but I just drive by them.

The sensible Swiss (and expats) do everything we can to find lower prices. :)

You will drive across a border station whenever you cross countries but they only stop cars very randomly - mostly to check if we've brought too much meat back with us from the grocery store!

It's possible you may get stopped briefly for a quick check but I never have. You do need to ensure your car has a Swiss Highway Vignette on it though (it is how they toll the roads here) which can be bought at gas stations just before or after the border. You can read more about that vignette's and other driving in Switzerland information here.